The present invention relates to a carbonaceous material derived from solid carbonaceous fossil fuel, subjected to deoxygenation, and where appropriate dewatering, in the presence of hydrogen and a solvent having hydrogen carrier properties.
In the so-called solvent refining of coal, which process can be applied to moderately high rank through to low rank coals, the coal, in a particulate condition, is subjected to liquefaction in a high-boiling solvent, (e.g. boiling between 200.degree. and 450.degree. C.), suitable as a hydrogen carrier (in a physical and/or chemical sense), at a temperature above 350.degree. C., say between 350.degree. and 500.degree. C. in the presence of hydrogen, at a pressure of about 30 to 250 bar. After having been subjected to this treatment for about 15 to 120, more particularly 50 to 90 minutes, the pressure is let down from the reaction product and the liqueform reaction mixture is subjected to a step of solids separation, usually filtration, in order to remove therefrom all non-dissolved matter, namely the char-like solids such as fusain and the ash. The clear liquid phase is then subjected to distillation whereby the solvent is recovered and recycled, whereas the substantially non-volatile bottoms of the distillation constitute the so-called solvent refined coal (SRC) which can serve as a feed stock for catalytic hydro-cracking. The object of the solvent-refining of coal, of which the solids removal step has always been an integral and essential part, is the obtaining of a feed stock of low oxygen and sulphur content and substantially free of substances which can harm the catalyst physically or chemically in the subsequent hydro-cracking step. Where SRC is advocated as a fuel, its low ash and sulphur contents are invariably quoted as favourable characteristics, which can make an important contribution towards air pollution abatement. The comparatively difficult solids removal step is thus an important and essential part of the known processes between the separation of ash and carbonaceous insolubles harmful to the catalyst or for other purposes, is one of the primary objects of such processes.
Conventional solvent refined coal (an essential characteristic of which is the virtual absence of ash) is known to have properties making it suitable for coking purposes. We had also observed that by blending a relatively small proportion of SRC with a poorly coking coal, the coking properties of the coal are substantially upgraded. However, the comparatively high cost of conventional SRC has militated against its production on a commercial scale and hence its use for that purpose.